I’m watching George Clooney leave the London cinema where he’s just been chatting about his latest film, The Ides of March.

While his co-stars get straight into their waiting cars and drive away, George spends several minutes pressing the flesh and posing for pictures with the small crowd that has gathered.

As he shakes hands and smiles, he looks just like a handsome politician on the campaign trail, like the man running for president who he plays in the movie.

But he insists that we will only see him as an elected representative on screen.

Partly because he says he doesn’t have a big enough ego – and also because of all the negative advertising he’d have to endure from opponents.

“There would just be shots of me in my rubber Batman suit and everyone would think ‘what an ass!’,” he smiles, referring to his slightly undignified turn as the Caped Crusader in the 1997 film Batman and Robin.

“I have a very good life, a comfortable existence. I like it much better where I am. If I want to dip my toe into political issues like Darfur and Sudan, I’m happy to do that and I don’t have to compromise.

“I grew up in a time when most people had a social and political conscience. I was raised to participate and I will continue to be as involved as much as I can. But I won’t be running for office.

“You would think that actors have this gigantic ego, and they do. But politicians have a tremendous amount too.

“The product you are selling to the entire country is yourself. All the time you are saying ‘I’m better than anyone else’. Ego is really tricky to embrace as a politician.

“There is a certain cut-throat nature to Hollywood, but with the exception of a few actors, most of us are pretty kind to one another. There’s a certain generosity with most actors that I certainly don’t see in politics.”

His father Nick, a former TV anchorman, made an unsuccessful bid to be elected to the US Congress in 2004 so Clooney knows something of the world of politics – and particularly the immense finances involved.

“It costs a couple of million dollars to run, even for a small Congressional district,” he says dejectedly.

“Right now, 95 per cent of the people who win elections have the most money. That’s a big part of elections.”

Clooney’s humanitarian efforts in Africa – he made a film to show the plight of Darfur’s refugees and spoke in front of the Security Council to ask the UN to find a solution to the conflict – led to him being one of only eight people to be named official United Nations Messengers of Peace.

He’s a liberal who opposed the Iraq War and supported Barack Obama in his election campaign.

Does he not feel that the American public has become more jaded about politics and their president?

“The message of hope has been dampened a bit,” he admits.

“But I feel fairly optimistic about the way our country works. We are going through a more cynical time in politics, but it’s all cyclical and we will get it back again.”

So what does he make of British politics? He is wise enough not to be drawn into criticism, but he does admit to enjoying watching coverage of House of Commons debates on television.

Putting on a posh English accent, he shouts “Order!”, adding: “It’s fun. It’s such a different way of doing things. We don’t do that.

“I can’t quite figure out what happens and I’m not sure who won.”

Currently dating model and former wrestler Stacy Keibler, he’s looking tanned and relaxed in jeans and a leather jacket.

Clooney has also directed Confessions of a Dangerous Mind, Good Night, and Good Luck and Leatherheads, but this is his first film set in the present day.

“It was a lot easier to direct a modern piece, I didn’t have to worry about airplanes flying through. Period pieces are a pain in the butt. I want to do more of these!”

Directing is clearly an important outlet: “I’ve been acting for a long time, and you start to realise that you need to continue to try things. Writing and directing is an incredibly creative process and acting is just one element in a film.

“When I fail as a director, it’s much more upsetting than when I fail as an actor, and when I succeed it’s more exciting. I like the risk involved.”